AP File PhotoSteven Jackson has had success against the Detroit Lions in the past and stopping him on Sunday will be the key to a Detroit victory.

Here are four things to keep your eye on when the Detroit Lions host the St. Louis Rams on Sunday.

First Down: Steven Jackson
The Lions struggled against the run last season, allowing opponents to average five yards per carry. They face a stiff test in Jackson, a versatile back who has gained at least 1,000 yards in seven consecutive seasons. In each of the last two meetings against the Lions, Jackson has gone over 100 yards, including a 149-yard outburst in the Rams' 17-10 victory in 2009, their only win that season.

If Detroit can bottle up the Rams running game, making their offense one-dimensional, it could be an easy day at the office for the Lions.

Second Down: Patchwork secondary
With Louis Delmas and Chris Houston expected to miss Sunday's contest, the Lions will take the field with an entirely different group from last season. Veterans John Wendling and Erik Coleman would get the nod at safety, while rookie cornerback Bill Bentley and either Jacob Lacey or Drayton Florence will be on the outside.

St. Louis quarterback Sam Bradford is coming off a disappointing season, but he's still a former No. 1 overall pick. If the Lions defensive line can't get consistent pressure, it could put the Lions' secondary in a tough spot.

Third Down: St. Louis offensive line
The Lions' defensive line should have success getting pressure against the Rams' offensive line. Last season, St. Louis gave up 55 sacks, more than any other team. Detroit returns all eight players from a defensive front rotation that registered 41 sacks last season. The group should be even better this year with a healthy Nick Fairley and the emergence of third-year pro Willie Young.

Fourth Down: Other side of the coin
Led by defensive end Chris Long (13 sacks in 2011), the Rams have also proven capable of generating a respectable pass rush. The key to the Lions' season is keeping quarterback Matthew Stafford upright and healthy.